Introduction

Cortisol is a steroid hormone and the predominant glucocorticoid secreted by the adrenal glands. Circadian rhythms regulate the amount and frequency of cortisol secretion. Blood cortisol levels peak just before waking in the morning and then gradually decline throughout the day to synchronize with the wake-sleep cycle [1]. Cortisol levels are influenced by a range of lifestyle factors, such as sleep, physical activity, diet, smoking, alcohol consumption, and mood [1-3]. Cortisol is involved in the regulation of many important bodily functions, including metabolism and stress, inflammatory, and immune responses [4]. Additionally, chronically elevated levels of glucocorticoids are associated with cardiovascular disease, obesity, and metabolic syndrome, as well as a tendency to develop infections, cancer, physical frailty, mood disorders, cognitive impairment, and memory problems [5].

Cigarette smoking is a harmful lifestyle associated with several serious diseases. It increases the risk of cardiovascular, respiratory, metabolic, musculoskeletal, nervous, and immune diseases and increases morbidity and mortality rates. During the past few years, the use of waterpipes and electronic (e)-cigarettes has rapidly emerged as a popular smoking style, especially among young people [6]. Similar to cigarette use, waterpipe [7] and e-cigarette [8] use can lead to numerous deleterious health consequences, such as cancer and respiratory, cardiac, and metabolic diseases. Importantly, smoking elevates cortisol levels at a rate primarily determined by nicotine exposure. This increase has been linked to difficulty in quitting smoking and increased stress [9-11].

Active lifestyles improve physical and mental health as well as overall health, well-being, and quality of life by reducing stress levels [1,12]. Conversely, physical inactivity substantially increases the risk of ischemic heart disease, cancer, and chronic lung diseases [13]. Exercise has also been implicated as part of a strategy to reduce the harm of smoking. It appears to mitigate the adverse health effects of smoking by reducing withdrawal symptoms and the desire to smoke [14].

However, to the best of our knowledge, the ameliorative effects of smoking and physical activity on cortisol levels have not been examined. Therefore, this study compared daytime cortisol levels in adults with low, moderate, and vigorous physical activity levels according to smoking status. More specifically, this study aimed to examine daytime cortisol levels in adults who smoked cigarettes, waterpipes, or e-cigarettes compared to nonsmokers, based on their level of physical activity. These results will help us understand the importance of physical activity in mitigating the negative effects of smoking on daytime cortisol levels.

Methods

Ethics statement: The study was approved by the Research Ethics Committee of the Jordan University of Science and Technology (approval No: JUST-53/149/2022). Informed consent was obtained from all participants prior to commencement of the study, after a detailed explanation of the study’s objectives and procedures.

1. Recruitment and design

Healthy men and women aged 18 to 80 years who could read and understand Arabic were invited to participate in the study. Individuals with cardiovascular, respiratory, endocrine, metabolic, musculoskeletal, or mental disorders that could have affected the results were excluded. Invitations to participate in the study were advertised on social media and in public places. Participants were also recruited from parks, shopping centers, academic institutions, and hospitals.

The study design was cross-sectional, comparative, and observational to determine the differences in plasma cortisol levels between cigarette, waterpipe, and e-cigarette users versus nonsmokers.

2. General information about the participants

Self-reported “Google Forms” (Google LLC, Mountain View, CA, USA) were used to collect demographic and socioeconomic information including age in years, body weight in kilograms, height in centimeters, sex, education, household income in Jordanian dinars (JD), and residence type (rural or urban). Household income was categorized as low (≤500 JD), medium (501–1,199 JD), and high (≥1,200 JD), while education was categorized as no more than high school, diploma/first degree university, and master’s/PhD degree.

3. Plasma cortisol

A total of 1,411 adults were recruited to participate in the study. To maintain a comparable number of participants in each smoking group (none, cigarettes, waterpipes, and e-cigarettes), the investigators monitored the number of participants in each group. Plasma cortisol levels were measured in 974 individuals including nonsmokers (n=237), cigarette smokers (n=230), waterpipe smokers (n=268), and e-cigarette smokers (n=239). Individuals included in the cortisol study were selected from the total number based on who was recruited first. Blood samples (5 mL) were collected from the participants in ethylenediaminetetraacetic acid tubes at 10:00 AM (±2 hours) [15]. No fasting or abstinence from smoking was required. Samples were immediately centrifuged at 500×g and plasma was separated and stored at −80°C until used. Plasma cortisol levels were determined using a commercial enzyme-linked immunosorbent assay (Human Cortisol ELISA Kit, catalogue number: EH0641) obtained from Fine Biotech (Wuhan, China). The detection range of the kit was 0.39 to 25 ng/mL, and its sensitivity was 0.234 ng/mL.

4. Smoking status

Information on smoking was obtained using a self-reported questionnaire. Participants were asked to indicate their smoking habits, including smoking type and frequency [16]. Potential participants who reported using more than one smoking type were excluded from the study. Cigarette smokers were defined as individuals who smoked more than 100 cigarettes and were still smoking. E-cigarette smokers were defined as individuals who had vaped more than 100 times and were still vaping. Waterpipe smokers were defined as individuals who smoked more than 100 waterpipes and were still using waterpipes [16].

5. Physical activity

The short form of the Arabic version of the International Physical Activity Questionnaire (IPAQ) was used to measure physical and sedentary activities. The questionnaire is self-reported and consists of seven questions to measure vigorous, moderate, and walking physical activities, as well as sedentary activity [17]. The IPAQ has demonstrated acceptable validity, reliability, and standardization [18,19].

6. Statistical analysis

IBM SPSS version 21 (IBM Corp., Armonk, NY, USA) was used for statistical data analysis. Means and percentages were used to report the data, with a p-value set at <0.05. Participants were classified according to their smoking status (i.e., none, cigarettes, waterpipes, or e-cigarettes). Physical/sedentary activities were classified as high or low (i.e., above or below the 50th percentile, respectively). A 4 (smoking status)×2 (physical activity/sedentary activity level) two-way analysis of covariance (ANCOVA) was used to compare plasma cortisol levels among the participants. Subsequently, one-way ANCOVA was used to compare plasma cortisol levels among participants with high versus low physical/sedentary activity. Post-hoc least significant difference comparisons were used to examine the differences between the subgroups. Relationships between cortisol levels and age, sex, body mass index (BMI), disease status, job type, education, and income were examined using multiple linear regression to identify confounders. Variables associated with plasma cortisol levels were considered confounders and were used in the ANCOVA.

Results

1. Patient characteristics

The study included 974 individuals encompassing nonsmokers (n=237), cigarette smokers (n=230), waterpipe smokers (n=268), and e-cigarette smokers (n=239). As shown in Table 1, the age, weight, height, and BMI ranges of the participants were 18 to 80 years, 39 to 150 kg, 150 to 195 cm, and 15.6 to 50.1 kg/m², respectively. Table 2 shows the participants’ average plasma cortisol level (197.2±107.3 ng/mL). Additionally, similar percentages of individuals smoked no cigarettes (23.9%), cigarettes (25.5%), waterpipes (26.5%), or e-cigarettes (24.2%). The majority of participants engaged in low (67.6%) versus high (32.4%) vigorous physical activity, while a similar percentage of individuals engaged in low versus high moderate physical activity, walking, total physical activity, and sedentary activity (Supplementary Table 1). Information regarding the frequency of use in each smoking group is provided in Supplementary Table 2.

2. Confounders

Among all potential confounders, linear regression analysis revealed a significant association of plasma cortisol levels with sex (p<0.001), education (p<0.03), income (p<0.01), and marital status (p<0.04). Subsequently, sex, education, income, and marital status were considered confounders and adjusted for in the ANCOVA.

3. Changes in daytime cortisol due to smoking: the importance of physical activity

The two-way ANCOVA shown in Fig. 1 revealed a main effect of smoking status (p<0.001) without vigorous physical activity (p>0.2) and interaction effects (p>0.3). Subsequent group comparisons showed greater (p<0.001) cortisol levels in the e-cigarette group than in the cigarette, waterpipe, and nonsmoker groups, with no significant differences (p>0.05) between the other groups.

According to the two-way ANCOVA shown in Fig. 2, the main effects of moderate physical activity (p>0.02) and smoking status (p<0.001) were found to have no interaction effect (p>0.3). Subsequent group comparisons showed greater (p<0.001) plasma cortisol levels in the e-cigarette group than in the cigarette, waterpipe, and nonsmoking groups, with no significant differences (p>0.05) between the other groups. An additional one-way ANCOVA stratified according to smoking type revealed that cortisol levels were reduced in individuals with higher versus lower participation in moderate physical activity among nonsmokers (p<0.05) and cigarette (p<0.005) smokers.

As shown in Fig. 3, two-way ANCOVA revealed a main effect of smoking status (p<0.001) without an effect of walking (p>0.2) and interaction effects (p>0.4). Subgroup comparisons showed greater (p<0.001) cortisol levels in the e-cigarette group than in the cigarette, waterpipe, and nonsmoking groups; however, no differences (p>0.05) were found between the other groups.

As shown in Fig. 4, two-way ANCOVA revealed a main effect of smoking status (p<0.001) without an effect of total physical activity (p>0.2) and interaction effects (p>0.4). Subgroup comparisons revealed greater (p<0.001) plasma cortisol levels in the e-cigarette group than in the cigarette, waterpipe, and nonsmoking groups; no differences (p>0.05) were found between the other groups. Furthermore, one-way ANCOVA stratified by smoking type revealed that cortisol levels were reduced (p<0.005) in individuals with higher versus lower participation in total physical activity in the cigarette group.

As shown in Fig. 5, two-way ANCOVA revealed a main effect of smoking status (p<0.001) without an effect of sedentary activity (p>0.1) and interaction effects (p>0.3). Subsequent group comparisons showed greater (p<0.001) plasma cortisol levels in the e-cigarette group than in the cigarette, waterpipe, and nonsmoking groups, and no differences (p>0.05) were found between the other groups.

A summary of the figure data and F- and p-values according to smoking classification is shown in the Supplementary Table 3.

Discussion

Elevated cortisol levels are associated with sleep disturbance [20], increased stress [21], cognitive decline [9], cardiovascular disease, obesity, metabolic syndrome, susceptibility to infection, cancer, physical weakness, and memory problems [5,22]. Tobacco smoking is a health hazard [23], and participation in physical activity can protect and restore well-being and quality of life [1]. However, the combined effects of different smoking styles and physical activity on daytime circulating cortisol levels remain unclear. Therefore, the current study examined daytime plasma cortisol levels in individuals who smoked cigarettes, waterpipes, and e-cigarettes versus nonsmokers.

According to these results, e-cigarette smoking was associated with elevated plasma cortisol levels. Uniquely, however, engaging in an active lifestyle seems to help cigarette smokers and nonsmokers attenuate circulating cortisol levels. Given the potential negative effects of elevated circulating cortisol levels, these results confirm the health hazards of smoking. Fortunately, physical activity seems to temper some of the harmful effects of smoking. However, physical activity alone is insufficient to restore circulatory cortisol levels in e-cigarette smokers. Further studies are required to confirm these findings and to verify these hypotheses.

The results revealed elevated plasma cortisol levels in e-cigarette smokers compared to those in cigarette smokers, waterpipe smokers, and nonsmokers. To the best of our knowledge, no studies have determined daytime plasma cortisol levels in waterpipe or e-cigarette smokers, whereas a few studies have reported elevated cortisol levels in cigarette smokers [3,24-27]. The current findings confirm the negative health effects of e-cigarettes, particularly on plasma cortisol levels. Given the negative effects of elevated circulating cortisol levels, strategies should be implemented to control the spread of e-cigarette smoking and to reduce cortisol levels among smokers.

The results also revealed that cortisol levels were reduced in individuals with higher versus lower participation in physical activity among the nonsmokers and cigarette smokers. This finding suggests that an active lifestyle helps cigarette smokers and nonsmokers attenuate cortisol levels. Consistent with the current findings, physical activity has been found to reduce cortisol levels [28-30], improve cognitive function [9] and modulate psychological stress [31]. This reduction in cortisol levels seems to help attenuate cravings and withdrawal symptoms in smokers [32]. These beneficial effects appear to depend on the extent of physical activity [9,33]. For example, short-term aerobic exercise resulted in diminished cortisol levels in smokers; however, this reduction was greater after 8 weeks of exercise training [9]. Additionally, jogging promotes a greater reduction in cortisol levels than walking [33].

The claim that e-cigarettes release harmless vapors is not true [34]. Although the toxin levels in e-cigarette aerosols are much lower than those in cigarette smoke, they still contain nicotine, ultrafine particles, and other toxic carcinogenic chemicals. In addition, during e-cigarette smoking, a heated solution containing propylene glycol or glycerin is inhaled, which is not observed in cigarette smoking [35]. However, the effect of the inhalation of these solutions on cortisol levels remains unknown; thus, further studies are needed.

Nicotine exposure may trigger cortisol production in the brain. Nicotine stimulates cholinergic receptors in the hypothalamus, a region responsible for processing emotions, altering subjective stress levels, and stimulating responses from the hypothalamic-pituitary-adrenal axis; this nicotine stimulation leads to cortisol production [36]. Conversely, cortisol may play an important role in nicotine metabolism, as sensitivity to nicotine tends to diminish under conditions of enhanced corticosteroid activity [37]. Several neurotransmitters mediate the effects of nicotine, which may explain the effectiveness of moderate exercise in reducing stress hormones [9].

In the current study, no relationship was found between physical activity and daytime plasma cortisol levels in waterpipe or e-cigarette smokers. Given the lack of research on the combined effects of waterpipe or e-cigarette smoking and physical activity on daytime circulating cortisol levels, it is difficult to compare the results. However, physical activity may not be sufficient to attenuate the toxicity of compounds found in e-cigarette products, such as propylene glycol or glycerin [35,38]. Therefore, further studies are required to identify the effects of e-cigarette and waterpipe smoking on daytime cortisol levels.

According to the current results, e-cigarette smoking might be associated with daytime cortisol levels, whereas maintaining an active lifestyle seems to attenuate cortisol levels in both cigarette smokers and nonsmokers. Therefore, there is a need to develop plans to restrain the spread of tobacco smoking and attenuate the harmful effects of tobacco products on health, particularly the elevated cortisol levels in e-cigarette smokers. Further studies are required to confirm these findings and hypotheses.

The inherent limitations of this study’s cross-sectional design must be acknowledged. The cross-sectional design does not allow the establishment of causality; thus, the results are inconclusive. Additionally, the participants were recruited from Jordan, a relatively small Middle Eastern country, which prohibits the generalization of the findings. Additionally, data on smoking and participation in physical and sedentary activities were collected using questionnaires, which are inherently subjective and biased. Therefore, laboratory and clinical studies are required to determine the effects of the compounds found in e-cigarettes and waterpipes on cortisol and other hormone levels. However, the current results serve as a platform for future multicenter longitudinal studies to determine the health effects of consuming various smoking products, particularly on cortisol levels. Finally, although we collected data on smoking frequency for each type of smoking, this variable was not included in the analysis to avoid complicating the manuscript with the number of parameters analyzed.

The current study examined the combined effects of physical activity and cigarette, waterpipe, and e-cigarette smoking versus nonsmoking on circulating cortisol levels in adults. The results indicated that e-cigarette smoking was associated with elevated plasma cortisol levels. Interestingly, maintaining an active lifestyle seemed to temper cortisol levels in both cigarette smokers and nonsmokers. However, physical activity may not be sufficient to attenuate the elevated cortisol levels associated with e-cigarette products. Further studies are required to verify the effects of e-cigarette and waterpipe smoking on daytime cortisol levels.

Supplementary materials

Article information

Conflicts of interest

No potential conflict of interest relevant to this article was reported.

Funding

This study was funded by a grant from the Jordan University of Science and Technology (grant number 488/2022) to MA.

Author contributions

Conceptualization, Data curation, Formal analysis, Funding acquisition: MA, OK; Methodology, Project administration, Software: MA; Writing-original draft: MA, OK; Writing-review & editing: MA, OK.

Fig. 1.

Plasma cortisol level according to smoking status and vigorous physical activity. ^*p<0.05, statistical significance versus none, cigarettes, and waterpipes. Data are presented as mean±standard error.

Fig. 2.

Plasma cortisol level according to smoking status and moderate physical activity. ^*p<0.05, statistical significance versus none, cigarettes, and waterpipes. ^†p<0.05, statistical significance versus high physical activity. Data are presented as mean±standard error.

Fig. 3.

Plasma cortisol level according to smoking status and walking physical activity. ^*p<0.05, statistical significance versus none, cigarettes, and waterpipes. Data are presented as mean±standard error.

Fig. 4.

Plasma cortisol level according to smoking status and total physical activity. ^*p<0.05, statistical significance versus none, cigarettes, and waterpipes. Data are presented as mean±standard error.

Fig. 5.

Plasma cortisol level according to smoking status and sedentary activity. ^*p<0.05, statistical significance versus none, cigarettes, and waterpipes. Data are presented as mean±standard error.

References

• 1. De Nys L, Anderson K, Ofosu EF, Ryde GC, Connelly J, Whittaker AC. The effects of physical activity on cortisol and sleep: a systematic review and meta-analysis. Psychoneuroendocrinology 2022;143:105843.ArticlePubMed
• 2. Jia R, Carlisle S, Vedhara K. The association of lifestyle and mood with long-term levels of cortisol: a systematic review. Cogent Psychol 2022;9:2036487.Article
• 3. Steptoe A, Ussher M. Smoking, cortisol and nicotine. Int J Psychophysiol 2006;59:228–35.ArticlePubMed
• 4. Oakley RH, Cidlowski JA. The biology of the glucocorticoid receptor: new signaling mechanisms in health and disease. J Allergy Clin Immunol 2013;132:1033–44.ArticlePubMedPMC
• 5. O’Byrne NA, Yuen F, Butt WZ, Liu PY. Sleep and circadian regulation of cortisol: a short review. Curr Opin Endocr Metab Res 2021;18:178–86.ArticlePubMedPMC
• 6. Ramôa CP, Eissenberg T, Sahingur SE. Increasing popularity of waterpipe tobacco smoking and electronic cigarette use: implications for oral healthcare. J Periodontal Res 2017;52:813–23.ArticlePubMedPMCPDF
• 7. Kakaje A, Alhalabi MM, Alyousbashi A, Ghareeb A, Hamid L, Al-Tammemi AB. Smoking habits and the influence of war on cigarette and shisha smoking in Syria. PLoS One 2021;16:e0256829. ArticlePubMedPMC
• 8. Esteban-Lopez M, Perry MD, Garbinski LD, Manevski M, Andre M, Ceyhan Y, et al. Health effects and known pathology associated with the use of E-cigarettes. Toxicol Rep 2022;9:1357–68.ArticlePubMedPMC
• 9. Al-Eisa E, Alghadir AH, Gabr SA, Iqbal ZA. Exercise intervention as a protective modulator against metabolic disorders in cigarette smokers. J Phys Ther Sci 2016;28:983–91.ArticlePubMedPMC
• 10. Slopen N, Kontos EZ, Ryff CD, Ayanian JZ, Albert MA, Williams DR. Psychosocial stress and cigarette smoking persistence, cessation, and relapse over 9-10 years: a prospective study of middle-aged adults in the United States. Cancer Causes Control 2013;24:1849–63.ArticlePubMedPMCPDF
• 11. McKee SA, Sinha R, Weinberger AH, Sofuoglu M, Harrison EL, Lavery M, et al. Stress decreases the ability to resist smoking and potentiates smoking intensity and reward. J Psychopharmacol 2011;25:490–502.ArticlePubMed
• 12. Childs E, de Wit H. Regular exercise is associated with emotional resilience to acute stress in healthy adults. Front Physiol 2014;5:161.ArticlePubMedPMC
• 13. Jackson SE, Brown J, Ussher M, Shahab L, Steptoe A, Smith L. Combined health risks of cigarette smoking and low levels of physical activity: a prospective cohort study in England with 12-year follow-up. BMJ Open 2019;9:e032852. ArticlePubMedPMC
• 14. Masiero M, Keyworth H, Pravettoni G, Cropley M, Bailey A. Short bouts of physical activity are associated with reduced smoking withdrawal symptoms, but perceptions of intensity may be the key. Healthcare (Basel) 2020;8:425.ArticlePubMedPMC
• 15. Al-Sharman A, Khalil H, El-Salem K, Aldughmi M, Aburub A. The effects of aerobic exercise on sleep quality measures and sleep-related biomarkers in individuals with multiple sclerosis: a pilot randomised controlled trial. NeuroRehabilitation 2019;45:107–15.ArticlePubMed
• 16. Khabour OF, Abu-Eitah RN, Alzoubi KH, Abu-Siniyeh A, Eissenberg T. The effect of genetic variations in the choline acetyltransferase gene (ChAT) on waterpipe tobacco smoking dependence. Tob Induc Dis 2020;18:27.ArticlePubMedPMC
• 17. Cleland C, Ferguson S, Ellis G, Hunter RF. Validity of the International Physical Activity Questionnaire (IPAQ) for assessing moderate-to-vigorous physical activity and sedentary behaviour of older adults in the United Kingdom. BMC Med Res Methodol 2018;18:176.ArticlePubMedPMCPDF
• 18. Craig CL, Marshall AL, Sjöström M, Bauman AE, Booth ML, Ainsworth BE, et al. International physical activity questionnaire: 12-country reliability and validity. Med Sci Sports Exerc 2003;35:1381–95.ArticlePubMed
• 19. Helou K, El Helou N, Mahfouz M, Mahfouz Y, Salameh P, Harmouche-Karaki M. Validity and reliability of an adapted Arabic version of the long international physical activity questionnaire. BMC Public Health 2017;18:49.ArticlePubMedPMCPDF
• 20. Morgan E, Schumm LP, McClintock M, Waite L, Lauderdale DS. Sleep characteristics and daytime cortisol levels in older adults. Sleep 2017;40:zsx043.ArticlePubMedPMC
• 21. Dziurkowska E, Wesolowski M. Cortisol as a biomarker of mental disorder severity. J Clin Med 2021;10:5204.ArticlePubMedPMC
• 22. Lightman SL, Birnie MT, Conway-Campbell BL. Dynamics of ACTH and cortisol secretion and implications for disease. Endocr Rev 2020;41:bnaa002.ArticlePubMedPMCPDF
• 23. Al-Tammemi AB. Tobacco epidemic in Jordan: the time to act is now. Glob Health Promot 2022;29:97–101.ArticlePubMedPDF
• 24. Chiodera P, Volpi R, Capretti L, Speroni G, Necchi-Ghiri S, Caffarri G, et al. Abnormal effect of cigarette smoking on pituitary hormone secretions in insulin-dependent diabetes mellitus. Clin Endocrinol (Oxf) 1997;46:351–7.ArticlePubMedPDF
• 25. Seyler LE, Fertig J, Pomerleau O, Hunt D, Parker K. The effects of smoking on ACTH and cortisol secretion. Life Sci 1984;34:57–65.ArticlePubMed
• 26. Badrick E, Kirschbaum C, Kumari M. The relationship between smoking status and cortisol secretion. J Clin Endocrinol Metab 2007;92:819–24.ArticlePubMed
• 27. Cohen A, Colodner R, Masalha R, Haimov I. The relationship between tobacco smoking, cortisol secretion, and sleep continuity. Subst Use Misuse 2019;54:1705–14.ArticlePubMed
• 28. Anderson T, Wideman L. Exercise and the cortisol awakening response: a systematic review. Sports Med Open 2017;3:37.ArticlePubMedPMCPDF
• 29. Duclos M, Tabarin A. Exercise and the hypothalamo-pituitary-adrenal axis. Front Horm Res 2016;47:12–26.ArticlePubMed
• 30. Fragala MS, Kraemer WJ, Denegar CR, Maresh CM, Mastro AM, Volek JS. Neuroendocrine-immune interactions and responses to exercise. Sports Med 2011;41:621–39.ArticlePubMed
• 31. Nguyen‐Michel ST, Unger JB, Hamilton J, Spruijt‐Metz D. Associations between physical activity and perceived stress/hassles in college students. Stress Health 2006;22:179–88.Article
• 32. De Jesus S, Prapavessis H. Affect and cortisol mechanisms through which acute exercise attenuates cigarette cravings during a temporary quit attempt. Addict Behav 2018;80:82–8.ArticlePubMed
• 33. Scerbo F, Faulkner G, Taylor A, Thomas S. Effects of exercise on cravings to smoke: the role of exercise intensity and cortisol. J Sports Sci 2010;28:11–9.ArticlePubMed
• 34. Grana RA, Ling PM, Benowitz N, Glantz S. Electronic cigarettes. Cardiology patient page. Circulation 2014;129:e490–2.ArticlePubMedPMC
• 35. Phillips B, Titz B, Kogel U, Sharma D, Leroy P, Xiang Y, et al. Toxicity of the main electronic cigarette components, propylene glycol, glycerin, and nicotine, in Sprague-Dawley rats in a 90-day OECD inhalation study complemented by molecular endpoints. Food Chem Toxicol 2017;109:315–32.ArticlePubMed
• 36. Wong JA, Pickworth WB, Waters AJ, al’Absi M, Leventhal AM. Cortisol levels decrease after acute tobacco abstinence in regular smokers. Hum Psychopharmacol 2014;29:152–62.ArticlePubMedPMC
• 37. al’Absi M, Hatsukami D, Davis GL, Wittmers LE. Prospective examination of effects of smoking abstinence on cortisol and withdrawal symptoms as predictors of early smoking relapse. Drug Alcohol Depend 2004;73:267–78.ArticlePubMed
• 38. Almomen S, Aldossari M, Khaleel Y, Altamimi M, Alharbi O, Alsuwaydani A, et al. Effect of glycerol concentration on levels of toxicants emissions from water-pipe tobacco smoking (WTS). BMC Public Health 2023;23:1858.ArticlePubMedPMCPDF

Figure & Data

References

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